JPH0428051Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention relates to a method for introducing a sample into an atomic absorption spectrometer in which chemical flame is the atomization means, and in particular a suction flow method for concentrating a small amount of sample solution online. Regarding analysis equipment.

[Prior art and its problems]

Atomic absorption spectrometers, which use chemical flame as an atomization means, are now widely used as devices capable of highly accurate analysis of multiple elements.

However, it has low sensitivity to heavy metals such as lead and cadmium, which are environmental pollutants. For this reason, various ideas have been made for sample introduction devices and attempts have been made to increase sensitivity, but none of them can be said to be sufficient.
Among various methods, the most reliable and simple method is to chemically concentrate the sample for analysis before supplying it to the analyzer. Examples of this concentration method include an organic solvent extraction method, a coprecipitation method, and an ion exchange resin method. In atomic absorption spectrometry, 3 to 4 ml of sample solution is usually required.
In order to obtain a concentration of 20 times or more using the above method, even if you use a sample of 20 ml or more, only 1 ml will be obtained after concentration, so depending on the sample, these concentration methods may not be applicable. . Furthermore, all of these conventional concentration methods are batch-type methods that are performed outside the device and are manually operated one after another, so the concentration process requires time and skill, and it is difficult to eliminate individual differences. Strict control of the method is necessary to maintain high accuracy. In addition, as mentioned above, since a large amount of samples are handled compared to the final required amount, the amount of reagents required increases, and when concentrating multiple samples at the same time, a large amount of equipment is also required. There were many problems with the conventional technology.

[Purpose of invention]

In order to solve the above-mentioned problems of the prior art, the present invention incorporates an ion exchange resin column for sample concentration into the sample processing system of the device, thereby reducing the amount of sample and quickly and efficiently. An object of the present invention is to provide an atomic absorption spectrometer using an online suction flow type chemical flame as atomization means, which enables highly sensitive analysis.

[Summary of the idea]

The apparatus of the present invention includes an atomic absorption spectrometer equipped with a sample injection section, an ion exchange resin column, a reagent and sample transfer pump, and a sample atomizer.

Depending on the type, ion exchange resins can adsorb elements or
It has selectivity regarding ion exchange. For example, when using a chelate resin, the selectivity is in the order of heavy metals>alkaline earth metals>alkali metals when the sample is neutral or has a pH of around 2. For example, seawater mainly contains alkali metals and alkaline earth metals, and when seawater is passed through a chelate resin, trace amounts of heavy metals in the seawater are preferentially adsorbed by the chelate resin over alkali metals and alkaline earth metals. This selectivity of chelate resins is utilized to collect heavy metals.
That is, even when this ion exchange resin has previously collected alkali metals and alkaline earth metals up to the limit of its ion exchange capacity, ion exchange between these two and heavy metals occurs due to the above-mentioned selectivity. are collected with priority. After adsorption of heavy metals, if a very small amount of acid is passed through, ion exchange with hydrogen occurs instantly, and heavy metal ions (elements of interest for analysis) are removed.
is released (eluted) from the chelate resin. In other words, trace amounts of heavy metal components in a large amount of seawater are dissolved in a small amount of acid, resulting in a high degree of concentration.

Since this chelate resin has a relatively large ion exchange capacity, a small amount of resin can adsorb a large amount of metal ions, and a resin column with a small capacity can sufficiently achieve the purpose. In addition, the smaller the volume of the heavy metal collected in the column, the more it becomes possible to elute the heavy metal with a smaller amount of acid, and the higher the concentration at the time of elution.

Specifically, in this invention, an analytical sample is flowed into a column in which a buffer solution (or purified water) is constantly flowing, the heavy metal ions contained therein are adsorbed on an ion exchange resin, and then a small amount of acid is flowed in to adsorb the heavy metal ions. The emitted ions quickly elute, and a sharp spike-like peak is obtained as a luminescence signal. Compared to the conventional batch method, the time required for the concentration process is shorter, and as mentioned above, the column capacity is small and the amount of acid used is small.
The buffer solution quickly returns the ion exchange resin to a state in which it can adsorb heavy metals again. Concentration mentioned above
The short time required for both return processes shortens analysis time and improves work efficiency.

In the conventional batch-type concentration method using ion exchange resin, the processes of natural dripping and repeated washing and elution with acid are all performed manually, and it is usually possible to process 20 samples per hour just by concentration and elution. Since this is submitted to an analyzer, the analysis time is added by approximately 1 hour. Therefore, the time required for concentration and analysis of 20 samples is 2 hours.

In comparison, in the method of the present invention, when 2 ml of sample solution is passed through an ion exchange resin column at a sample feeding rate of 2 ml/min, the passage time is about 1 minute. Heavy metals adsorbed on the ion exchange resin in the column are eluted with a trace amount of acid, but because the column capacity is minute, the resin quickly returns to a pH that allows heavy metal adsorption. Therefore, the number of samples that can be analyzed using this method is approximately 20 or more per hour, which is extremely efficient compared to the batch method described above.

[Effect of idea]

Compared with conventional methods, the method of the present invention provides the following effects.

(1) Analysis is possible even when the sample solution to be analyzed is as small as 1 ml or less.

(2) Even if the analysis sample solution exhibits extremely high acidity, it can be used for analysis if a certain amount of the sample solution is mixed with a sufficient amount of acidity adjustment solution to make it neutral.

(3) Compared to the conventional batch-type concentration method, the present invention requires less time for concentration and a shorter time for restoring the ion exchange resin to its original state by the buffer solution, which shortens analysis time and improves work efficiency.

(4) The method of this invention has a high degree of concentration, and even when the analysis sample solution is 5 ml, the analytical sensitivity is improved by about 10 times compared to the conventional method, and the sensitivity improves even more when a larger amount of sample is used. do.

(5) Since acids, etc. are introduced in addition to the sample solution into the flow of buffer solution, the operating conditions are constant compared to conventional batch-type manual processing, eliminating individual differences and providing excellent reproducibility. Therefore, no skill is required, and the analysis accuracy is high.

(6) By adopting a control unit that automatically operates the autosampler or fraction collector connected to the sample collection unit, as well as the injection of acid into the column and the washing of the column, the photometry unit can be easily operated from the sample collection unit. It is possible to automate consistent analysis operations.

[Example of idea]

An embodiment of the present invention will be described below with reference to the drawings. However, Figure 1 shows the basic configuration of the present invention,
FIG. 2 shows an embodiment of the present invention. In FIG. 1, when a sample solution of 5 ml is normally collected with a sample collector such as a micropipette and injected into the sample injection part 1, it is passed through a constant flow pump 3 to a buffer solution (for example, 0.1
Introduced into the stream of molar sodium citrate solution) 2, while passing through the ion exchange column 5, heavy metals are captured on the ion exchange resin, while other alkali metals or alkaline earth metals pass through the column to the chemical flame 7. . Next, instead of the sample, add 0.1M hydrochloric acid to buffer solution 2.
The mixture becomes strongly acidic and enters the ion exchange column 5. Since the ion exchange resin releases (elutes) the collected metal ions when the pH is below 2.0, these metal ions are sprayed into the chemical flame 7 through the atomizer 6. The metal atoms produced by the thermal energy of the chemical flame absorb the resonance lines emanating from the hollow discharge tube of the target element. Its absorbance is proportional to the amount of metal ions present, that is, the content of metal elements. In other words, the atomic absorption phenomenon can be detected using an atomic absorption spectrometer 8.
Measure with.

Figure 2 shows an embodiment of the present invention in which an automation mechanism is added to the configuration of Figure 1.
2. Using a sample detector 11, an acid 10, a constant flow pump 4 for introducing the acid, and a controller 9 consisting of a timer. Here, the automatic sample collection section 12 is connected to an autosampler or a fraction collector, and a controller 9 controls sample collection. At the same time, the injection of acid into the column by the constant flow pump and the injection of a washing buffer solution into the column are also controlled by the controller 9 and the sample detector 11.

That is, when the sample collection constant flow pump 3 connected to the automatic sample collector 12 finishes collecting the solution sample and, if necessary, purified water for cleaning the inside of the sample collector, the detector 11 in the flow path detects the completion of sample introduction. The controller 9 operates based on this signal,
Constant flow pump 3 stops. When all of the sample solution, etc. has been introduced into the resin column 5, the controller 9 sends an activation signal to the constant flow pump 4 for a certain period of time, and hydrochloric acid is sent to the resin column 5. The metal ions are eluted by this hydrochloric acid and reach a chemical flame via an atomizer, resulting in an atomic absorption signal.

FIG. 3 shows the above working steps. A is 5 ml of sample solution, B is 0.25 ml of 1.0M hydrochloric acid, and C is buffer solution 1.
ml, D is ion adsorption (concentration), E is elution, F
indicates each step of washing, and T indicates the passage of time. The metal ions contained in the injected sample solution A are adsorbed by the ion exchange resin and concentrated D. Next, the metal ions are eluted by acetic acid B introduced into the ion exchange resin, and after the elution is completed, the ion exchange resin is washed F by a buffer solution C.

[Brief explanation of the drawing]

FIG. 1 is a flow path diagram showing the basic structure of the present invention, and FIG. 2 is a system diagram showing the schematic structure of an embodiment of the present invention. FIG. 3 is an explanatory process diagram of the present invention. DESCRIPTION OF SYMBOLS 1... Sample injection part, 2... Buffer solution, 3... Constant flow pump, 4... Constant flow pump, 5... Chelate resin column, 6... Sprayer, 7... Chemical flame, 8
... Atomic absorption spectrometer, 9 ... Controller, 10 ...
Hydrochloric acid, 11...sample detector, 12...automatic sample collection section, 13...constant flow pump, A...sample solution,
B... Hydrochloric acid, C... Buffer solution (or purified water),
D...Ion adsorption (concentration), E...Elution, F...
Washing, T...time.

Claims (1)

[Scope of utility model registration request] A sample collection unit that automatically collects a sample solution containing heavy metals, an eluent source consisting of a buffer solution source and hydrochloric acid, and a plurality of constant flow rates for selectively sucking the sample solution, buffer solution, and eluent, respectively. configuring a preconcentration channel including a pump and a chelate resin column for circulating the liquid discharged by the constant flow pump, and connecting an outlet line of the preconcentration channel to a sprayer of an atomic absorption spectrometer; A sample detector is connected to the sample collecting section, and a controller is provided for sequentially controlling the plurality of constant flow pumps in response to a sample detection signal from the sample detector, so that a continuously flowing buffer solution has a constant flow rate. The method is characterized in that, after the sample solutions are combined and flowed into the chelate resin column, the eluent is combined with the buffer solution and sent to the chelate resin column, and the concentrated sample is eluted from the column. Atomic absorption spectrometer.